1. Field of the Invention
The present invention relates to insulated entrance systems for buildings and more particularly to a door/window having a heat insulating frame member comprising a pair of inside and outside metal members interconnected by a heat insulating spacer therebetween. A door/window or closure member of the invention is also useful in combination with a heat insulating type wall frame system forming an entrance opening in which the door/window is mounted. In addition, the invention also encompasses the conversion of existing non-insulating type closure members into more heat efficient members by the application of heat insulating spacers and metal cladding elements thereto to provide thermally efficient windows and doors for building walls and entrances.
2. Description of the Prior Art
With the advent of the energy crisis and ever increasing fuel costs, many different types of heat insulating building walls, doors, windows and entrances have been proposed. The following U.S. Pat. Nos. disclose efforts in this area to provide more heat efficient structures and are listed as follows: 2,933,779; 2,985,263; 3,099,337; 3,203,053; 3,204,324; 3,267,629; 3,335,524; 3,527,011; 3,624,885; 3,818,666; 3,861,085; 3,975,881; 3,978,629; 4,067,163; 4,118,266; 4,128,934; 4,164,830; and 4,187,657.